Re: New conflict message in latest GIT

From: Bjorn Helgaas
Date: Wed Jul 23 2008 - 14:57:19 EST

On Tuesday 22 July 2008 12:56:36 pm Fabio Comolli wrote:
> Linus' GIT tree 2.6.26-05752-g93ded9b shows this message:
> i801_smbus 0000:00:1f.3: PCI INT B -> GSI 19 (level, low) -> IRQ 19
> ACPI: I/O resource 0000:00:1f.3 [0x18e0-0x18ff] conflicts with ACPI
> region SMBI [0x18e0-0x18ef]
> ACPI: Device needs an ACPI driver
> There is no equivalent in 2.6.26 or previous kernels.

The "ACPI: I/O resource ... conflicts with ..." message was added by

That conflict checking infrastructure was in 2.6.26, but Jean's
change to make the i801_smbus driver use it didn't happen until
about a week ago:;a=commitdiff;h=54fb4a05af0a4b814e6716cfdf3fa97fc6be7a32

The message is telling us that the i801_smbus driver thinks it owns
the 0x18e0-0x18ff region, but there's also an ACPI opregion that
references that region. There's no coordination between ACPI and
the i801_smbus driver, so there may be issues where nearly
simultaneous accesses cause incorrect behavior, e.g,. one may
read the wrong value from a temperature sensor. That, of course,
can lead to more serious things like unintended machine shutdowns.

I don't have any ideas about how to address this. I think Thomas's
intent was to collect better information for unreproducible bugs.
(Maybe this sort of conflict should even set a taint flag?)


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